CMake - dependencies (headers) between apps/libraries in same project

Question

I have the following project structure:

• CMakeLists.txt
  • lib1/CMakeLists.txt and all cpp and header files of the lib
  • lib2/CMakeLists.txt and al

Answer 1

Here's one possible solution:

Root CMakeLists.txt:

cmake_minimum_required(VERSION 2.8 FATAL_ERROR)
project(${PROJECT_NAME})
add_subdirectory(lib1)
add_subdirectory(lib2)
add_subdirectory(app)

lib1/CMakeLists.txt:

project(Lib1)
add_library(lib1 lib1.cpp lib1.h)

lib2/CMakeLists.txt:

project(Lib2)
add_library(lib2 lib2.cpp lib2.h)

# Add /lib1 to #include search path
include_directories(${Lib1_SOURCE_DIR})
# Specify lib2's dependency on lib1
target_link_libraries(lib2 lib1)

app/CMakeLists.txt:

project(App)
add_executable(app main.cpp some_header.h)

# Add /lib1 and /lib2 to #include search path
include_directories(${Lib1_SOURCE_DIR} ${Lib2_SOURCE_DIR})
# Specify app's dependency on lib2.
# lib2's dependency on lib1 is automatically added.
target_link_libraries(app lib2)

There are plenty of different ways to achieve the same end result here. For a relatively small project, I'd probably just use a single CMakeLists.txt:

cmake_minimum_required(VERSION 2.8 FATAL_ERROR)
project(Test)

add_library(lib1 lib1/lib1.cpp lib1/lib1.h)
add_library(lib2 lib2/lib2.cpp lib2/lib2.h)
add_executable(app app/main.cpp app/some_header.h)

include_directories(${CMAKE_SOURCE_DIR}/lib1 ${CMAKE_SOURCE_DIR}/lib2)

target_link_libraries(lib2 lib1)
target_link_libraries(app lib2)

For further info on the relevant commands and their rationale, run:

cmake --help-command add_subdirectory
cmake --help-command include_directories
cmake --help-command target_link_libraries